According to Brown University's Cost of War project analysis, authored by Neta Crawford, the total estimated cost of U.S. wars between 2001 and 2018 amounts to about $23,386 per individual American taxpayer, which is more than three times the amount ($7,740) calculated by the Pentagon.

The Pentagon's study, dubbed the "Estimated Cost to Each Taxpayer for the Wars in Afghanistan, Iraq, and Syria," places the total authorized war spending on those conflicts between 2001 and 2018 at $1.5 trillion.

Unlike assessments conducted by the Pentagon and other analysts, Crawford's estimate takes into account trillions in conflict-linked spending appropriated mainly through the U.S. Departments of Homeland Security, State, Defense, and Veteran Affairs.